Skip Navigation The Harold Leever Regional Cancer Center

Daniel O'Neil, MD, MPH

203-755-6311  |  fax: 203-755-6263

Daniel O'Neil, MD, MPH, has been named an Assistant Clinical Professor of Medicine (Medical Oncology) and cares for patients with breast cancer as part of the Smilow Cancer Hospital Care Center in Waterbury. Dr. O'Neil joined Yale Cancer Center and Smilow Cancer Hospital from the University of Miami where he was an Assistant Professor of Clinical Medicine.

Dr. O’Neil received his medical degree from Albert Einstein College of Medicine, completed residency at Brigham and Women’s Hospital in both Internal Medicine and Global Health Equity, and completed fellowship at New York Presbyterian/Columbia University Medical Center. He received his MPH with a focus on epidemiology at Harvard T.H. Chan School of Public Health. Dr. O’Neil treats women with breast cancer of all stages and subtypes, as well as women with high-risk benign breast lesions. He strongly believes in the value of multidisciplinary patient care and collaboration. He aims to incorporate the latest evidence-based practices, alongside a holistic understanding of each of his patients, to offer truly personalized care. He is active with Yale Cancer Center’s breast cancer research team and offers patients at the Smilow Cancer Hospital Care Center in Waterbury access to clinical trials. Dr. O’Neil’s own research addresses disparities in breast cancer care and outcomes, particularly in low- and middle-income countries, and in women living with HIV.